THUNDERSTORMS MERGE TO FORM ‘SUPER CLOUD’ OVER EAST COUNTY

The public got an unusually clear look Tuesday at three thunderstorms forming into one powerful, 15-mile wide “super cloud” that produced heavy rain at Mount Laguna, Pine Valley and Banner. Such consolidation is rarely visible because the skies typically feature lots of nearby clouds that obscure what’s happening.

The super cloud arose from monsoon moisture from Baja California. A thunderstorm formed about 2 p.m. south of the border, near Boulevard. A second storm formed a short time later along Interstate 8. Both were consumed around 3 p.m. by a stronger thunderstorm that took shape over Pine Valley.

The system’s warm, moist air quickly rose up the south face of Mount Laguna. The cloud soon grew to about 15 miles in diameter.

The moist air cooled and turned icy as it rose. But it had enough energy to form an anvil-shaped cap about 50,000 feet above the ground, when the system touched the stratosphere and spread in a north-south direction.

For more than 30 minutes, the midsection of the super cloud seemed to billow with smoke. In reality, it was proof that new clouds were forming.

The super cloud dropped more than an inch of rain in the Mount Laguna-Pine Valley area and drenched Warner Springs and Banner. Its power literally drained away as hail fell within the cloud and rain dropped to the ground. From start to finish, the super cloud lasted about 75 minutes, dying around 4:15 p.m.

Meanwhile, the Sunday downpour that caused flash flooding in Borrego Springs — sending water and mud flowing though parts of the town — has prompted county officials to set up sandbag stations there and in Julian.

Free sand and bags are available at Cal Fire Station 50 in Julian, 1587 state Route 78. Residents must bring their own shovel, according to the county government.

In Borrego Springs, free bags are available at the Sheriff’s Department substation at 571 Palm Canyon Drive.